1. Technical Field
The present invention relates to a data write control method of a hard disk drive, and more particularly, relates to a method for controlling a data write operation by sensing an abnormal flying height of a transducer head.
2. Related Art
Hard disk drive is widely used as an auxiliary storage device of a computer system because its large storage capacity and data access speed. Each hard disk drive typically includes one or more magnetic disks installed at a driving axle of a spindle motor rotating at high speed and an actuator rotatably installed at a pivot axle to support a transducer head for writing or reading data in or from successive tracks of the disk. A bobbin and a coil are installed at one end of the actuator to rotate by operation of a voice coil motor. Then, the transducer head which is installed at a distal end of the actuator rotates in a radial direction of the disk for writing or reading data on or from the track. Generally, the transducer head moves while maintaining a minute flying height by an air flow generated by the high speed revolution of the disk. The movement of the magnetic head is caused by reproduction of servo information written in a servo sector of the disk.
A typical servo sector of an arbitrary track of the magnetic disk is composed of a preamble region for synchronizing with a system clock, a servo address mark (SAM) region for recording a reference pattern for producing various servo timing signals, an index (IDX) region for supplying single rotation information of the disks, a gray code region for providing identification (ID) information of each track, a servo burst region typically consisting of servo burst signals A, B, C and D for the on-track control of the heads, and a postamble region. The servo burst signals A and B are respectively written with a half value in adjacent tracks and used for the on-track control of the transducer head during track follow-up. The amplitude levels of the servo burst signals vary according to the position and the flying height of the transducer head. However, if the flying height of the transducer head is higher than a normal flying height because of external shock or poor surface uniformity of the disk, I have observed that it is difficult to perform data read/write operations. This is particularly acute if the data write operation is implemented while the transducer head maintains the flying height higher than the normal flying height. Data will be lost and abnormal data will be written onto the disk as described in U.S. Pat. No. 5,377,058 for a Fly Height Servo Control of Read/write Head Suspension issued to Good et al., and U.S. Pat. No. 5,588,007 for a Method for Detecting Transient Write Errors in a disk drive issued to Ma. While these servo control techniques provide reliable data storage reliability can still be contemplated.